1. Field of the Invention
The present invention relates to a display device, a driving method of the display device and an electronic apparatus, and particularly relates to a planar-type display device in which pixels each having an electro-optic device are arranged two-dimensionally in a matrix state, a driving method of the display device and an electronic apparatus having the display device.
2. Description of the Related Art
In recent years, in a field of display devices performing image display, a planar-type (flat-panel type) display device in which pixels (pixel circuits) are arranged in a matrix state is becoming popular rapidly. As one of the planer-type display devices, there is a display device using a so-called current-driven type electro-optic device as a light-emitting device of the pixel, in which light emission luminance varies according to a current value flowing in the device. As the current-driven type electro-optic device, an organic EL device is known, which uses electroluminescence (EL) as an organic material and utilizes a phenomenon of emitting light when an electric field is applied to an organic thin film.
An organic EL display device using the organic EL device as the light-emitting device of the pixel has the following characteristics. That is, the organic EL device is a low-power consumption device as the device can be driven by application voltage of 10V or less. The organic EL device has high visibility of images as compared with a liquid crystal display device because the device is a self luminous device, and further, the device can be light and thin because a lighting member such as a backlight is not necessary. Moreover, the organic EL device has extremely high response speed of approximately several μsec, therefore, residual images do not occur.
The organic EL display device can apply a simple (passive) matrix type and an active matrix type as a driving method thereof in the same manner as the liquid crystal display device. Though the simple matrix display device has a simple structure, a light emission period of the electro-optic device is reduced by the increase of scanning lines (namely, the number of pixels), therefore, there is a problem such that it is difficult to realize a large-sized and high definition display device.
In response to the above, the active matrix display device controlling electric current flowing in the electro-optic device by an active device which is, for example, an insulating-gate field-effect transistor provided in the same pixel where the electro-optic device is provided is under vigorous development in recent years. As the insulating-gate field-effect transistor, a TFT (Thin Film Transistor) is commonly used. In the active matrix display device, the electro-optic device maintains light emission during a period of one display frame, therefore, the large-sized high definition display device can be easily realized.
A pixel circuit having the current-driven type electro-optic device which is driven in the active matrix method includes the electro-optic device as well as a drive circuit for driving the electro-optic device. The pixel circuit having the drive circuit including a drive transistor 22, a write transistor 23 and a storage capacitor 24 is known, which drives an organic EL device 21 as the current-driven type electro-optic device (for example, refer to JP-A-2008-310127 (Patent Document 1).
In Patent Document 1, it is disclosed that a scanning line potential (write scanning signal) WS is allowed to fall at the falling timing of a power supply voltage Vdd2 by using the power supply voltage Vdd2 which falls immediately in a pulse state (refer to Paragraph No. 0116 and so on in Patent Document 1). It is also disclosed in Patent Document 1 that a threshold correction period is defined by the rising timing of a power supply line potential DS and the falling timing of the scanning line potential WS (refer to Paragraph No. 0117 and so on in Patent Document 1).
Also in Patent Document 1, it is further disclosed that writing of a video signal is performed when the write scanning signal WS is in an active state (refer to Paragraph No. 0062 and so on in Patent Document 1). It is further disclosed in Patent Document 1 that mobility correction which corrects variations in mobility of transistors in respective pixels is performed in parallel to the writing of the video signal (refer to Paragraph No. 0064 to No. 0067 and so on in Patent Document 1). A signal writing period and a mobility correction period are determined by the pulse width of the write scanning signal.